pid1: preserve current value of log target across re-{load,execution}

To make debugging easier, this patches allows one to change the log target and
do reload/reexec without modifying configuration permanently, which makes
debugging easier.

Indeed if one changed the log target at runtime (via the bus or via signals),
the change was lost on the next reload/reexecution.

In order to restore back the default value (set via system.conf, environment
variables or any other means ), the empty string in the "LogTarget" property is
now supported as well as sending SIGTRMIN+26 signal.

diff --git a/man/elogind.xml b/man/elogind.xml
index bfe130e9872c1714e1446fffc23629cc54953485..a0162399ec60e9d02688d840d3485ecc674adf22 100644 (file)
--- a/man/elogind.xml
+++ b/man/elogind.xml
@@ -862,20 +862,21 @@
 
       <varlistentry>
         <term><constant>SIGRTMIN+26</constant></term>
+
+        <listitem><para>Restores the log target to its configured value. The configured value is derived from – in
+        order of priority – the value specified with <varname>systemd.log-target=</varname> on the kernel command line,
+        or the value specified with <option>LogTarget=</option> in the configuration file, or the built-in
+        default.</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
         <term><constant>SIGRTMIN+27</constant></term>
         <term><constant>SIGRTMIN+28</constant></term>
 
-        <listitem><para>Sets the log target to
-        <literal>journal-or-kmsg</literal> (or
-        <literal>console</literal> on
-        <constant>SIGRTMIN+27</constant>, <literal>kmsg</literal> on
-        <constant>SIGRTMIN+28</constant>), as controlled via
-        <varname>systemd.log_target=journal-or-kmsg</varname> (or
-        <varname>systemd.log_target=console</varname> on
-        <constant>SIGRTMIN+27</constant> or
-        <varname>systemd.log_target=kmsg</varname> on
-        <constant>SIGRTMIN+28</constant>) on the kernel command
-        line.</para></listitem>
+        <listitem><para>Sets the log target to <literal>console</literal> on <constant>SIGRTMIN+27</constant> (or
+        <literal>kmsg</literal> on <constant>SIGRTMIN+28</constant>), in a fashion equivalent to
+        <varname>systemd.log_target=console</varname> (or <varname>systemd.log_target=kmsg</varname> on
+        <constant>SIGRTMIN+28</constant>) on the kernel command line.</para></listitem>
       </varlistentry>
     </variablelist>
   </refsect1>